Process for drying yarn



- Julie 10, 1941. J.:VUYTENBOGA,ART ETAL 2,244,744

PROCESS FOR DRYING YARN Filed Aug. 11, 1937 2 Sheets-Sheet l I Fig.1.

Fused Si/fca 2,244,744 June 10 194 J. UYTENBOGAART ETAL I PROCESS FOR DRYING YARN t 2 hee Filed Aug. 11, 1937 2 Sheets 3 MU fenbggaarf I Ca /lfram I N Patented June 10, 1941 PROCESS FOR DRYING YARN Johannes Uytenbogaart, Berlin- Lichterfelde, Germany, and Carl F. Gram, Elizabethton, Tenn, assignors to North American Rayon Corporation, New York, N. Y., a corporation of Delaware Application August 11, 1937, Serial No. 158,496

4 Claims.

The present invention relates to the heating of rotating surfaces but more specifically has for its object to provide a heating element for thread conveying rollers whereby yarn or thread conveyed on such rollers may be uniformly and thoroughly dried during their passage thereover.

The device is particularly adapted for use in machines used in the continuous production of artificial silk. In machines such as these the filaments are extruded through a precipitating bath and conveyed to rollers over which they pass in an approximately helical path. The filaments may be given the different wet-treatments necessary while on the rollers such as desulphurizing, deacidifying, etc., and immediately thereafter, and while still on the same rollers or when passed to other rollers, dried.

For the continuous manufacture of artificial filaments groups of rollers, two or more, may be employed. The rollers are so arranged in their relation to one another that the thread is automatically conveyed in an approximately helical path from one end of the said rollers to the other end thereof. Apparatus such as the above described is disclosed and illustrated in a copending application, Serial No. 730,662, filed June 14, 1934, and entitled, Process for treating artificial filaments and apparatus therefor.

In this copending application, above identified. is disclosed a pair of rollers at an angle, one to the other, and both rollers rotating on axes which are at an angle to the horizontal. The drying of the filaments takes place on the upper roller at its upper end. A gas flame is used to heat the rotating rollers at a point with which the filaments are not at the moment of application of the heat, in contact. This method of heating has proven quite satisfactory in those localities where gas is available. In this invention, however, it is proposed to use an electrical heating element for the drying of the threads.

Heretofore, where any electrical elements have been used for heating the interior of rotating surfaces a great disadvantage has resulted due to the fact that a. rotating contact must be used. With such contacting means the passage of current therehrough is not uniform and they have the additional drawback that wear quickly results and replacement of the worn contacts must be made. Further, during the wearing process the flow of current becomes even more irregular, resulting in yarn which has not been uniformly dried, a serious consequence particularly in the manufacture of artificial silk.

Another feature of applicants invention resides in so designing the heating element that the greatest amount of heat contacts the thread immediately after the after-treatment and while the threads contain the greatest amount of moisture. As the threads pass along the heating zone decreasing heat is applied as the threads lose their moisture thus resulting in a more uniformly dried thread. A further advantage of this idea of decreasing the heat as the moisture content of the filaments decreases is that it is less likely that damage will result to the threads which because of a decreasing moisture content become more susceptible to heat damage. Also by reducing the temperature drop, or better, maintaining a fairly constant decrease in temperature throughout the drying zone results in less internal strain in the filaments.

It is therefore one object of the present invention to devise a. heating element for rotating surfaces which does not rotate with the surface thus heated.

Another object of the present invention is to devise a stationary heating element for the interior of rotating cylinders which may quickly and easily be removed and replaced without the necessity of stopping production operations.

Still another object of the present invention is to devise a'heating element and method which will dry the threads uniformly and with less danger of damage caused by heat treatment.

These and other objects will in part become obvious and will in part be pointed out in the following specification. and appended claims when taken in conjunction with the attached drawings, in which:

Fig. 1 is a side elevation of a portion of a pair of spaced cylinders with the filaments passing thereover and the novel heating element comprising the invention illustrated in operative posi-' In the drawings, in which like numerals of reference indicate like parts, I and 2 refer to the cylinders over which the filaments 3 pass in an approximately helical path.

The cylinder I has extending therein the heating element 6. The cylinders l and 2 are rotated by any suitable driving mechanism (not shown). I

Adjacent the cylinder I is mounted a support 5 which serves the double purpose of carrying the power conduit wires and supporting the heating element l. Mounted on the support 5 is a bracket member I which carries the power outlet receptacle 8 and has formed therein in axial alinement with said power outlet 8 a socket 9.

The heating element 4 comprises a hollow bracket arm l2 which carries connecting wires It. At one end of the bracket I2 is formed a socketed extension I5 which carries a plug it having the usual contact members I l.

The socketed extension l5 carrying the plug It is removably mounted in the socket 9 of the bracket 5 thereby forming the electrical contact and mounting means.

Formed at the opposite end of the bracket 12 are radial supporting arms 16 on which is mounted an insulating disc ll insulated from the arms I6 which may be of asbestos and forms a heat shield H. The shield fl'l fits within the inner circumferences of the hollow cylinder l and out of contact therewith. This heat shield acts to keep the heat within the cylinder thereby decreasing the amount of heat lost.

Mounted on the shield disc it is a bracket It to which is bolted at 20 the conical support I9 of the resistance coil H3.

The ends 2! and 22 of the resistance coil M are attached to terminals 23 and 2a to which one end the connecting wires l3 are attached. The other ends of the wires it lead into the plug it.

A peep-hole 25 is bored in the disc H so that the operator of the machine may ascertain at any time, without removal of the heating element, whether, the element is operating.

As hereinbefore pointed out, the heating element support I9 is tapered so that at one end there is a greater heat intensity than at the other end of the heating zone.

The threads 3 as they begin to pass over the heated portion of the cylinder 5 are in wet condition and therefore less susceptible to heat. As the filaments pass along the heated portion of the roller and gradually lose their moisture content there is less need for heat and the threads are less protected.

By tapering the heating element as illustrated in the drawings the source of heat is nearer to the wall of the cylinder and the coil is longer at that point where the threads are carrying the greatest amount of moisture, and the threads therefore receive the greatest amount of heat. As the threads pass along the heated surface of the cylinder, due to the tapering of the heating element inwardly, less heat is emitted and reaches the cylinder thus decreasing the heat of drying as the threads decrease in moisture content.

By decreasing the amount of heat as the threads or filaments lose their moisture content a more advantageous drying results with less chance of damage to the filaments.

It is to be understood that the form of the invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention, or the scope of the subjoined claims.

From the foregoing description, taken in connection with the accompanying drawings it is thought the complete construction, operations and advantages of the invention will be clear to those skilled in the art to which it relates.

What is claimed is:

1. In a process for drying wet thread or yarn on a heated rotating surface, the steps comprising, passing the thread in an approximately helical path over said surface, controlling the temperature of the surface so that the greatest amount of heat contacts the thread at the beginpassing the thread in an approximately helical path over said surface and gradually decreasing the temperature of said surface as the moisture content of the thread decreases in the course of the drying operation.

3. In a process for drying filaments, thread or yarn on a heated rotating surface having zones of gradually diminishing temperatures, the steps comprising, continuously passing wet thread over said surface and causing the thread to first contact the zone having the maximum temperature and thereafter to gradually contact zones of lower temperatures as the drying operation progresses, said maximum temperature being of a magnitude insufficient to damage the thread.

4. In a process for gradually drying continuous lengths of filaments, thread or yarn on a heated rotating surface having zones of gradually diminishing temperatures, the steps comprising, passing the thread over said surface, causing the thread to have contact with the zone having the maximum temperature at the beginning of the drying operation and thereafter progressively passing the thread over the surface through the zones of gradually diminishing temperatures, the thread contacting the zone having the lowest temperature at the end of the drying operation.

JOHANNES UYTENBOGAART. CARL F. GRAM. 

